You simply just have to believe in Ki as a force within and outside the body that you can control with your mind. I am not talking about ki balls or flashes of energy, but there is something there and the mind is where the control start....
How you learn how to do that is a very individual thing since there just is not a step by step process to recognize and learn it. But it can be taught -

a few thoughts ... i think: another way to connect with your post
As an example:
-your heart consumes energy and beats automatically. you don't have to believe in it. But you can effect it with your beliefs (imagine someone kicking your dog. Dammit).
-it is effected by your subconscious as well as mediated by your autonomic system
-you can train your body to take control of normally subconscious/automatic things and train and refine them. Visualization can be used to tap into this. I think this is where what you call 'belief' can accurately be mapped to 'intent' by others. my opinion.
-you can feel and know -it- directly. but it does require training to become sensitive to 'the water we, as fish, swim in'. The fish analog here is to the energy in the human body<, part of which is under volitional control; and part under the brain/subconscious. 'belief' is one way to tap into the subconscious. it can be dangerous; as you are messing with your very own Tuner.
-in fact this 'belief' part, I find, is where it can fork off into a million other things (potentially delusional). This was helpful to me:: 'the energy can play with your mind'. In my thinking: Don't forget we are talking about hacking both the hardware(body/shenfa/chi) and software (mind/body programming/methods/shenfa /chi(yes; counted in both columns)/balance/proprioception/flexing patterns/etc). We are talking about changing the way things 'work' today... and I think it would be negligent to think changing them doesn't have subsequent effects somehow (i.e.... and how we see, feel and think with that very same hardware platform)
just some thoughts you put in my head! All only "In my opinion". Errors are mine alone.